Everything You Always Wanted to Know About Infidelity But Were Afraid to Ask

July 24, 2013

A reader recently asked me for some stats around infidelity, and I was surprised to realize that in over 700 posts, I’ve never written a summary of the research on cheating. It’s actually remarkably consistent overall, and for obvious reasons, we all stand to benefit from knowing the red flags that signal a person’s likelihood to succumb to infidelity in a committed relationship. 

Here’s the latest research. You might want to grab coffee or a glass of wine, it’s going to be a long post. Don’t shoot me, I’m just the data junkie piano player.

Many thanks to Megaman for his analyses and graphics.

Most Recent Finding

The percentage of wives having affairs rose almost 40 percent during the last two decades to 14.7 percent in 2010, while the number of men admitting to extramarital affairs held constant at 21 percent, according to the latest data from the National Opinion Research Center’s General Social Survey.


Results vary by age. Among Baby Boomers, age 49-66, 29% of males and 16% of females admitted to cheating. This is probably close to the lifetime rate, and perhaps differs by generation as well:


In contrast, Gens X and Y, ages 18-48, show a similar rate among females (15%) and much lower rate among males (20%).


Why the increase in female cheating overall?

Wives with their own jobs have less to lose economically from a divorce, and social media have made it easier to engage in affairs.

…The main impetus behind extramarital affairs was predictable, Djamba said: One in four men described their marriages as “not very happy,” more than twice the number of wives who rationalized their adultery that way.

Who’s cheating most?

Blacks, executives and managers, and Southerners were most likely to report extramarital affairs to the 40-year-old survey, the oldest continuous source of data on American behavior.

Relationship history is key.

People who have been divorced or separated are twice as likely to cheat:

For men it’s 28% vs. 14%:


And for women it’s 19% vs. 7%:


The previous number of sexual partners is also highly predictive for men:


and women:


A Plethora of Stats

From Kinsey:

● 11% of adults who have ever been married or cohabited have been unfaithful to their partner (Treas & Giesen, 2000).

● Infidelity is influenced by many social and demographic factors. All of the following were associated with an increased risk of infidelity:

  1. having been part of a couple for a long time
  2. having had a high number of prior sex partners
  3. being male or black
  4. living in a central city
  5. thinking about sex several times a day 

● Respondents who reported that their relationships were “pretty happy” and “not too happy” were two and four times more likely, respectively, to have reported extramarital sex than respondents who reported that they were “very happy” with their relationships (Atkins et al., 2001). 

● 94% of married men and women had only one sex partner (their spouse) in the past 12 months, 4% had 2-4 partners, and 1% had over 5 partners (Laumann, Gagnon, Michael, Michaels, 1994). 

Cheating by kissing is twice as common as intercourse:

Statistics from American Association for Marriage and Family Therapy, say only 15% of wives report having had sex outside of their marriage. Like men, the number does go up when you include emotional affairs or things like kissing — 35% of wives admit to that.

25% of husbands report having had sex outside of their marriage. When emotional affairs or sexual intimacy without intercourse (such as kissing) are included, the number jumps to 45%.

It often starts at the office:

● Individuals who work outside the home while their partners remain in the home also express higher rates of extramarital sexual involvement (Atkins et al., 2001), perhaps because the work environment provides the opportunity and time to get to know coworkers (Treas & Giesen, 2000).

● In clinical samples, 46% to 62% of individuals reported that they met their extramarital sexual partner at work (Glass, 2003; Wiggins & Lederer, 1984).

● The likelihood of extramarital involvement is also related to the degree to which an individual’s job involves touching clients, discussing personal concerns with colleagues or clients, or working alone with co-workers (Treas & Giesen, 2000).

Motives for cheating:

48% of men rated emotional dissatisfaction as the primary reason they cheated.

So much for the myth that for men, cheating is all about sex: Only 8 percent of men said that sexual dissatisfaction was the main factor in their infidelity. 

66% of cheating men report feeling guilt during the affair.

The implications are a little scary: It isn’t just uncaring jerks who cheat. In fact, 68 percent of cheaters never dreamed they’d be unfaithful, and almost all of them wished they hadn’t done it.

Only 12% of cheating men said their mistress was more physically attractive than their wife.

In other words, a man doesn’t stray because he thinks he’ll get better sex with a better-looking body. “In most cases, he’s cheating to fill an emotional void. He feels a connection with the other woman, and sex comes along for the ride.

Only 6% of cheating men had sex with a woman after meeting her that same day or night.

Actually, 73 percent of men got to know the other woman for more than a month before they cheated. 

On the other hand…

Experts say that most often, men and women have different reasons for being unfaithful. Men search for more sex or attention, and women look to fill an emotional void.

Women tend to have an emotional connection with their lover and are more likely to have an affair because of loneliness.

Fifty-six percent of men who had affairs were happy in their marriage, according to a study by Helen Fisher, PhD, a biological anthropologist at Rutgers University and the author of Why Him? Why Her? and Why We Love.  By comparison, only 34% of women who had affairs were happy or very happy in their marriage.

Men are more likely to give sexual motivations for infidelity and less likely to fall in love with an extramarital partner, Fisher tells WebMD. “Women are more interested in supplementing their marriage or jumping ship than men are. For men, it is a secondary strategy as opposed to an alternate.”

Gender roles are important predictors of cheating behavior:

● Women do not like being the dominant partner.

The imbalance of power in the primary relationship has been associated with infidelity. Edwards and Booth (1976) found that wives who reported that they “get their way” more often during disagreements were also more likely to have extramarital sexual involvements.

● Income plays a role.

A Cornell University study on income and infidelity found that women are least likely to stray when they depend on their husband’s income. They may have fewer opportunities to cheat and may decide it isn’t worth it because their livelihood may be at risk.  

Ironically, the same Cornell University study found that men who bring home most of the household income are also more likely to cheat. Men were least likely to cheat when their partners made about 75% of their incomes.

● So does education.

A National Marriage Project study found that highly educated people are less likely to be unfaithful than their less educated peers. In the 2000s, 13% of people with a college education said they had sex outside their marriage, compared to 19% of those who were moderately educated and 21% of those with the least education (high school dropouts).

In a large U.S. national study of dating, cohabiting, and married women, Forste and Tanfer (1996) found that women who were more educated than their husbands were more likely to engage in sexual infidelity; but if the husband was more educated than the wife, she was less likely to philander. Level of education relative to that of the partner appears to be more important than absolute level of education.

● In addition, intelligence in males is correlated to lower incidence of infidelity:

Data from a large, representative American sample shows that more intelligent boys are more likely to grow up to value sexual exclusivity in early adulthood than less intelligent boys.  In contrast, childhood IQ does not affect girls’ value on sexual exclusivity in early adulthood.  The effect of intelligence on the value of sexual exclusivity is more than four times as strong among men than among women.  Among women, the association is not statistically significant.

Sexual exclusivity is an “evolutionary novel” quality that would have been of little benefit to early man, who was programmed to be promiscuous. The modern world no longer confers such an evolutionary advantage to men who have several sexual partners – but it is only intelligent men are able to shed the psychological baggage of their species and adopt new modes of behaviour.

Physiology is important:

1. Measure resting heart rate.

Extreme sports athletes and men who seek excitement tend to engage in all kinds of arousing events, including illicit affairs. These men have low resting heart rates. Bomb disposal professionals and parachutists also have low resting heart rates. These under-aroused individuals also commit more crimes–violating social norms gets them the excitement they crave. 

2. Measure testosterone.

A man’s present testosterone can be assessed by looking at his face (jaw jutting out, prominent cheekbones), body hair (hairy means more testosterone, but very high testosterone causes male pattern baldness–yes, baldies are alpha males), deep voice, and muscularity. [Demerits] for a longer fourth to second finger, more than average hairiness, and a long jaw.

3. Measure emotional range.

If you spot a misty eye when the guy gets the girl at the end of the movie, or the little boy succumbs to cancer, he’s got an intact oxytocin system.

And so are personality traits:

For men, significant predictors of infidelity are personality variables, including propensity for sexual excitation (becoming easily aroused by many triggers and situations) and concern about sexual performance failure.

The latter finding might seem counterintuitive, but other studies have also found this connection. “People might seek out high-risk situations to help them become aroused, or they might choose to have sex with a partner outside of their regular relationship because they feel they have an ‘out’ if the encounter doesn’t go well — they don’t have to see them again.”

…All kinds of things predict infidelity. What this study says is that when you put all of those things together, for men, personality characteristics are so strong they bounce everything else out of the model. For women, in the face of all other variables, it’s still the relationship that is the most important predictor.

For college students, there are four key predictors for cheating in a committed, sexual relationship:

  1. a respondent’s number of sexual partners
  2. level of dysfunctional impulsivity
  3. satisfaction with current relationship
  4. quality of relationship alternatives (this was the strongest predictor)

We also found that males reported a greater inclination to engage in extradyadic sex than females, although no significant effect of gender was found in the prediction of extradyadic kissing inclination. 

 Sociosexuality is highly relevant:

As predicted, we report a significant interaction between sex-love-marriage and commitment in the prediction of extradyadic sex inclination, such that higher sex inclination was reported only amongst people who are low in sex-love-marriage associations and low in commitment. 

The interaction revealed that among females, extradyadic inclination was lower for those with a greater cognitive association of sex-love-marriage. However, for males, there was no such interaction.

● Half of the men and women in the top (withinsex) 20% of sociosexuality have been sexually unfaithful to a steady partner. This is more than double the average rate of infidelity in the population.

● Women in the top female quintile of sociosexuality are nearly as elevated in their relevant sexual experiences as men in the top male quintile.

● Table 1. Comparison of Top  Quintiles on Self-Reported Behavioral Correlates of the Sociosexuality Scale Scores in Percentages (2000)*

Had sex with someone the same day
you met
Got pregnant, or got someone
pregnant, before marriage
Had sex after having a lot to drink7788
Was unfaithful to a steady partner4863
Had sex with two people in a 24 hour
Ever had a sexually transmitted disease1924


But familiarity does not breed contempt, with all due respect to Coolidge:

However, relationship duration was not found to be significant in the prediction of either extradyadic kissing or sex inclination. 

An avoidant attachment style also predicts cheating in college students:

Some 68 percent had thought about cheating and 41 percent had actually cheated. Sexual satisfaction aside, the results indicated a strong correlation between infidelity and people with an avoidant attachment style.

Infidelity could be a regulatory emotional strategy used by people with an avoidant attachment style. The act of cheating helps them avoid commitment phobia, distances them from their partner, and helps them keep their space and freedom. The will to distance themselves from commitment and their partner was the number one reason cited.

Just as many men and women had an avoidant attachment style and the correlation with infidelity is just as strong on both sides.

A survey of 1002 undergraduate students found that those who reported [having rebound relationships after a breakup] were more likely to have cheated on a previous partner. The complete profile of the average rebounder doesn’t get much better, either:

Undergraduates who were ‘love seekers”, “deceptive”, “unconventional” and “hedonistic/ risk takers” were significantly more likely to report having been involved in a rebound relationship.

Societal attitudes towards infidelity are hardening:

In a 2006 poll by the Pew Research Center, 88% of Americans said adultery was immoral — a higher number than for any other of 10 unsavory behaviors they were asked about.

In a 2009 Gallup Poll, only 6% of Americans believe extramarital sex is morally acceptable.

According to the GSS, Americans are becoming less tolerant of  extramarital relationships over time:

In 2006, 80.6 percent of Americans said that infidelity is always wrong – up from 73.4 percent in 1991. (Another 14.6 percent in 2006 said that infidelity is “almost always wrong.”)

In the 2008 Gallup Values and Beliefs poll, Americans as a group found extramarital affairs morally worse than polygamy, human cloning, and suicide.

However, only 50 or 60 percent of Americans say that adultery would be an automatic deal breaker for their marriage.

Finally, some cheating is rebellion:

Children who are raised with harsh proscriptions against sex often desire the forbidden fruit. They may also become the most moralistic adults in an effort to keep their own yearnings at bay (which explains the hypocrisy we so often see among busted conservative religious and political leaders). It is probably not a coincidence that Utah has the highest number of Internet searches of any state for the term “hot girls”.

Now you know what to look out for. It shouldn’t be as overwhelming as it sounds – most of these traits overlap considerably in individuals. Caveat emptor.